A differential pressure transducer is a device which provides an output which is the difference between two input pressures. For example, when a Pressure P1 is applied to one face of a deflecting diaphragm and a pressure P2 is applied to the other face of the deflecting diaphragm the resulting deflection will be determined by the difference in pressure (as for example P1-P2). There are other differential pressure transducers which essentially use two separate semiconductor structures each structure having its own diaphragm and the piezoresistor devices which are employed on the diaphragm surface are connected together to form a bridge which will provide a differential output. Reference is made to U.S. Pat. No. 6,595,066 entitled Stopped Leadless Differential Sensor issued on Jul. 22, 2003 to AD Kurtz, et. al. and assigned to the assignee herein. That patent shows a differential transducer where the pressure is applied to the top face or the top side of the diaphragm and to the bottom face or bottom side of the diaphragm to obtain a differential output. The patent shows a Wheatstone Bridge array consisting of piezoresistors which vary resistance according to the magnitude of a pressure or force applied to the diaphragm.
However, in prior art devices which utilize a force applied to two separate diaphragms, there is a problem in low pressure devices to bring out the leads. This problem resulting in one of the diaphragms of the differential transducer being smaller than the other diaphragm. In any event, it is known that the diaphragm size effects the operation of such a device. The larger the diaphragm, the less the back pressure, and the larger the diaphragm, the more compliant the diaphragm is. Therefore a large diaphragm is more compliant and will experience less back pressure than a smaller diameter diaphragm. Thus the prior art devices because of the problem in bringing out the leads as will be further explained had and required two different size diaphragms, one diaphragm being larger in diameter than the other diaphragm thus, resulting in pressure variations which compromised the operation of such devices.
Therefore, is an intention of the present invention to provide a low pressure differential transducer having the same size diaphragm while enabling one to bring out the leads from the semiconductor sensor in a simple and expeditious manner.